EP0625850A2 - Appareil d'enregistrement et de reproduction de signaux numériques - Google Patents

Appareil d'enregistrement et de reproduction de signaux numériques Download PDF

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Publication number
EP0625850A2
EP0625850A2 EP94107527A EP94107527A EP0625850A2 EP 0625850 A2 EP0625850 A2 EP 0625850A2 EP 94107527 A EP94107527 A EP 94107527A EP 94107527 A EP94107527 A EP 94107527A EP 0625850 A2 EP0625850 A2 EP 0625850A2
Authority
EP
European Patent Office
Prior art keywords
recording
magnetic
head
tape
recorded
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP94107527A
Other languages
German (de)
English (en)
Other versions
EP0625850A3 (fr
Inventor
Tadashi Kunihira
Hiroshi Okamoto
Makoto Gotou
Yoshio Sakakibara
Toshio Inaji
Eiji Ueda
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP5114454A external-priority patent/JPH06325305A/ja
Priority claimed from JP5179013A external-priority patent/JPH0737209A/ja
Priority claimed from JP5183712A external-priority patent/JPH0744804A/ja
Priority claimed from JP05254083A external-priority patent/JP3119053B2/ja
Priority claimed from JP5254180A external-priority patent/JPH07110903A/ja
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Publication of EP0625850A2 publication Critical patent/EP0625850A2/fr
Publication of EP0625850A3 publication Critical patent/EP0625850A3/fr
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B15/00—Driving, starting or stopping record carriers of filamentary or web form; Driving both such record carriers and heads; Guiding such record carriers or containers therefor; Control thereof; Control of operating function
    • G11B15/02—Control of operating function, e.g. switching from recording to reproducing
    • G11B15/12—Masking of heads; circuits for Selecting or switching of heads between operative and inoperative functions or between different operative functions or for selection between operative heads; Masking of beams, e.g. of light beams
    • G11B15/125—Masking of heads; circuits for Selecting or switching of heads between operative and inoperative functions or between different operative functions or for selection between operative heads; Masking of beams, e.g. of light beams conditioned by the operating function of the apparatus
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B15/00—Driving, starting or stopping record carriers of filamentary or web form; Driving both such record carriers and heads; Guiding such record carriers or containers therefor; Control thereof; Control of operating function
    • G11B15/18—Driving; Starting; Stopping; Arrangements for control or regulation thereof
    • G11B15/1808—Driving of both record carrier and head
    • G11B15/1875—Driving of both record carrier and head adaptations for special effects or editing
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/008—Recording on, or reproducing or erasing from, magnetic tapes, sheets, e.g. cards, or wires
    • G11B5/00813—Recording on, or reproducing or erasing from, magnetic tapes, sheets, e.g. cards, or wires magnetic tapes
    • G11B5/00847—Recording on, or reproducing or erasing from, magnetic tapes, sheets, e.g. cards, or wires magnetic tapes on transverse tracks
    • G11B5/0086—Recording on, or reproducing or erasing from, magnetic tapes, sheets, e.g. cards, or wires magnetic tapes on transverse tracks using cyclically driven heads providing segmented tracks
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/02—Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
    • G11B5/09—Digital recording
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/76—Television signal recording
    • H04N5/91—Television signal processing therefor
    • H04N5/92—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback
    • H04N5/926—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback by pulse code modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/76—Television signal recording
    • H04N5/91—Television signal processing therefor
    • H04N5/92—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback
    • H04N5/926—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback by pulse code modulation
    • H04N5/9261—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback by pulse code modulation involving data reduction
    • H04N5/9264—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback by pulse code modulation involving data reduction using transform coding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N5/00—Details of television systems
    • H04N5/76—Television signal recording
    • H04N5/78—Television signal recording using magnetic recording
    • H04N5/782—Television signal recording using magnetic recording on tape
    • H04N5/783—Adaptations for reproducing at a rate different from the recording rate

Definitions

  • the present invention relates to recording and playback apparatus for digital signals, such as digital VTRs and PCM tape recorders, that compresses digital signals such as video signals, audio signals and the like to record on magnetic tape.
  • digital signals such as digital VTRs and PCM tape recorders
  • recording and playback apparatus for digital signals makes its recorded-track pitch in a long-play recording mode narrower than its recorded-track pitch in a standard-play recording mode. Therefore, It requires narrow magnetic heads in the long-play recording mode so that the total number of magnetic heads increases.
  • recording and playback apparatus for digital signals varies the rotational speed of the rotary cylinder and the traveling speed of the magnetic tape in agreement with the recorded-data rate. For example, if the recorded-data rate decreases by 50 %, then the rotational speed of the rotary cylinder and the traveling speed of the magnetic tape are reduced by 50 %.
  • the object of the present invention is therefore to provide a recording and playback apparatus for digital signals that performs recording in the long-play recording mode or at a different bit rate without adding extra magnetic heads and with the same recorded-track pitch as in the standard-play recording mode.
  • Another object of the present invention is to provide a recording and playback apparatus for digital signals that accommodates a plurality of recorded-data rates without changing the rotational speed of the rotary cylinder and performs high-density recording by azimuth recording.
  • a further object of the present invention is to provide a recording and playback apparatus for digital signals that plays back all recorded digital information at variable playback speed to obtain almost the same reproduced images as in standard playback.
  • a recording and playback apparatus for digital signals of the present invention comprises a rotary cylinder that has at least one pair of magnetic heads, one head having a different azimuth from the other, a tape-speed control means that controls the traveling speed of the magnetic tape wrapped around the rotary cylinder, a magnetic-head selection means that selects a magnetic head during recording so that adjacent helical tracks have different recording azimuths, and a recording means that records on the magnetic tape once every n (n ⁇ 2, integer) scans of the magnetic heads mounted in the rotary cylinder.
  • the above apparatus has a compression encoding means that compresses and encodes a digital signal to be recorded depending on the traveling speed of the magnetic tape.
  • high-density recording is made possible by azimuth recording, and digital information is compressed to record by the compression encoding means depending on the traveling speed of the magnetic tape.
  • a recording and playback apparatus for digital signals of the present invention comprises a rotary cylinder that has at least one pair of magnetic heads, one head having a different azimuth from the other, a tape-speed control means that controls the traveling speed of the magnetic tape wrapped around the rotary cylinder, a magnetic-head selection means that selects a magnetic head during recording so that adjacent helical tracks have different recording azimuths, a first-mode recording means that moves the magnetic tape at a standard speed by the tape-speed control means and records digital information on the magnetic tape during each scan of the magnetic heads mounted in the rotary cylinder, and a second-mode recording means that records digital information of less amount than for the first mode on the magnetic tape once every n (n ⁇ 2, integer) scans of the magnetic heads mounted in the rotary cylinder.
  • the present invention can records with almost the same track width without adding magnetic heads in the second mode where digital information of less amount than for the first mode is recorded.
  • the tracking accuracy in the second mode can be made the same as in the first mode.
  • head touches are stabilized.
  • high-density recording is made possible by azimuth recording.
  • a recording and playback apparatus for digital signals of the present invention comprises a rotary cylinder that has at least one pair of magnetic heads, one head having a different azimuth from the other, a tape-speed control means that controls the traveling speed of the magnetic tape wrapped around the rotary cylinder, a magnetic-head selection means that selects a magnetic head during recording so that adjacent helical tracks have different recording azimuths, a bit-rate conversion means that converts input signals of several bit rates into digital information of a predetermined recording bit rate, and a recording means that records digital information and system information once every n (n is a positive integer) scans of the magnetic heads depending on the bit rates of the input signal.
  • a recording and playback apparatus for digital signals of the present invention comprises a rotary cylinder that has at least one pair of magnetic heads, one head having a different azimuth from the other, a tape-speed control means that controls the traveling speed of the magnetic tape wrapped around the rotary cylinder, a recording mode in which digital information is recorded once every n (n ⁇ 2, integer) scans and the magnetic tape is moved at a predetermined speed by the tape-speed control means so that successively recorded two tracks become contiguous to each other, a playback mode in which the rotational speed of the rotary cylinder is made almost the same as in the recording mode, and digital information is played back during each scan of the magnetic heads, and a magnetic-head selection means that selects a magnetic head that scans in the recording and playback modes.
  • two pairs of magnetic heads are mounted in the rotary cylinder, one head having a different azimuth from the other and one pair being positioned 180 degrees from the other, and recording is made on the magnetic tape once every n (n ⁇ 3, odd number) scans of the magnetic heads, so that the objective of the present invention is realized by a simplest composition of the cylinder.
  • Fig. 1 shows a block diagram of a recording and playback apparatus for digital signals of a first embodiment in accordance with the present invention.
  • 1 is magnetic tape
  • 2 is a rotary cylinder
  • 3 is magnetic heads, that is, two pairs of magnetic heads (R1, L1) and (R2, L2) mounted in rotary cylinder 2, where Ri have azimuth R, and Li have azimuth L, and (R1, L1) are positioned opposite to (R2. L2) at an angle of 180 degrees.
  • Fig. 2A shows an example of set azimuths of the pair (R1, L1) of magnetic heads
  • Fig. 2B shows an example of set azimuths of the pair (R2, L2) of magnetic heads.
  • the azimuths of R1 and R2 are the same
  • the azimuths of L1 and L2 are the same.
  • the magnetic heads R1 and L1 are positioned shifted away from each other by a level difference x in the rotary cylinder
  • the heads R2 and L2 are positioned shifted away from each other by the level difference distance x.
  • This level difference x is set so that the widths of tracks formed on the magnetic tape during recording become one desired track-pitch.
  • Fig. 1 4 is a pinch roller, 5 is a capstan, 6 is a capstan motor, 7 is a tape-speed control circuit, 8 is a mode command generation circuit for generating a compression mode command responsive to operation of a selection switch 12, 9 is an input terminal for digital information, 10 is a compression encoding circuit, and 11 is a magnetic-head selection circuit.
  • magnetic tape 1 is wrapped around rotary cylinder 2 at an angle of about 180 degrees but in an oblique direction, and moved by pinch roller 4 and capstan 5.
  • Tape-speed control circuit 7 controls the rotational speed of capstan motor 6 following a compression-instruction signal input through the compression-mode command generation circuit 8, so that the traveling speed of magnetic tape 1 becomes a predetermined velocity.
  • compression encoding circuit 10 compresses digital information input through the digital-information input terminal 9 following the compression-mode command from mode command generation circuit 8.
  • Magnetic-head selection circuit 11 selects a magnetic head from magnetic heads 3 so that the azimuths of adjacent recorded tracks of magnetic tape 1 on which information compressed by compression encoding circuit 10 is recorded become different.
  • Fig. 3 shows an example of the composition of compression encoding circuit 10.
  • a digital signal input through a terminal 100 is first transformed from values of a time domain into values of a frequency domain by a DCT (discrete cosine transform) circuit 101.
  • the transformed values are input to a quantization circuit 102 to be quantized.
  • the quantized values are treated by entropy encoding circuit 103, to be encoded.
  • Compression encoding circuit 10 compresses digital information at a compression ratio indicated by the compression-mode command. Compression of digital information is realized by at least one of DCT circuit 101, quantization circuit 102, and entropy encoding circuit 103.
  • the compressed digital signal is output through a terminal 104.
  • the DCT discrete cosine transform
  • MPEG Motion Picture Expert Group
  • Figs. 4 and 5 show timing during recording when a digital signal is recorded.
  • (a) denotes a head-switching signal
  • (b) denotes recorded tracks
  • (c) denotes used magnetic heads and recording intervals.
  • Fig. 4 is a timing chart in a recording mode.
  • Magnetic-head selection circuit 11 selects R1 and L1 of magnetic heads 3, which perform recording, at an interval when the head-switching signal is at "H”.
  • Magnetic-head selection circuit 11 does not select any magnetic heads at an interval when the head-switching is at "L", so that recording is not performed.
  • digital information input through digital-information input terminal 9 is recorded on magnetic tape 1 using one pair of magnetic heads (R1, L1) in one side of rotary cylinder 2, that is, while rotary cylinder 2 makes one revolution, two tracks are continuously recorded with track width Tp.
  • the traveling speed of magnetic tape 1 is set by tape-speed control circuit 7 so that two tracks are formed while rotary cylinder 2 makes one revolution. Since the azimuth of a track being recorded is different from the azimuth of its adjacent tracks, recording can be made without any gap between adjacent tracks, so that high-density recording is realized.
  • Fig. 5 is a timing chart in another recording mode (long-play recording mode), where the amount of recorded digital information is 1/2.5 the one in the recording mode of Fig. 4.
  • the amount of recorded digital information is 1/2.5 the one in the recording mode of Fig. 4.
  • the traveling speed of magnetic tape 1 is 1/2.5 the tape speed in the recording mode of Fig. 4, since the amount of recorded information is 1/2.5.
  • the rotational speed of rotary cylinder 2 is the same as in the recording mode of Fig. 4. Since two tracks are recorded, while rotary cylinder 2 makes 2.5 revolutions, recorded tracks are recorded on magnetic tape 1 with track width Tp without any gap between adjacent tracks as in Fig. 4. In this way, recording is performed once while rotary cylinder 2 makes 2.5 revolutions, that is, magnetic heads 3, (R1, L1) and (R2, L2), make 5 scans in all. Also, since (R1, L1) and (R2, L2) of magnetic heads 3 alternately perform recording, the azimuths of adjacent recorded tracks are different, as clear from Figs. 2A and 2B.
  • magnetic heads 3 can play back the same recorded tracks twice, so that a recorded digital signal can be obtained by collecting pieces of reproduced information having greater S/N ratios and by rearranging them. Therefore, in this case, tracking of high accuracy is not necessary during playback.
  • a recorded signal is reproduced without loss of information at a speed of up to 2.5 times the recording speed, where magnetic heads 3 play back each track twice.
  • playback can be performed without rigorous tracking at a playback speed up to n/2 the recording speed, at which at least two scans are made during playback. Therefore, the speed of data transfer during playback can be made n/2 the speed of data transfer during recording, so that data transfer to other recording media such as a disk recording medium can be performed at high speed.
  • reproduced digital data can be temporarily stored in a memory, and only desired data can be output. For example, in image data, stroboscopic playback is made possible.
  • the rotational speed of rotary cylinder 2 does not vary depending on the amount of digital information, the relative speed between magnetic tape 1 and magnetic heads 3 can be almost constant, and conditions on the contact between magnetic heads 3 and magnetic tape 1, that is, head touches can be made uniform independently of recording modes. Therefore, recording on and playback from magnetic tape 1 of a signal is performed well.
  • magnetic heads 3 mounted in rotary cylinder 2 consist of two pairs of heads, one pair positioned opposite to the other at an angle of 180 degrees.
  • one head can be used in place of a pair of heads.
  • two pairs can be mounted in one position in stead of diametrically opposite positions.
  • Fig. 6 shows a rotary cylinder in which two magnetic heads having different azimuths are positioned opposite to each other at an angle of 180 degrees.
  • Fig. 7 shows timing during recording in case this rotary cylinder is used and the amount of recorded digital information is 1/5 the amount of original digital information.
  • (a) denotes a head-switching signal
  • (b) denotes recorded tracks
  • (c) denotes used magnetic heads and their recording intervals.
  • heads R and L of magnetic heads 3 positioned opposite to each other at an angle of 180 degrees alternately perform recording, while rotary cylinder 2 makes 2.5 revolutions, that is, 5 scans.
  • the azimuths of adjacent tracks can be made different by recording once every odd scans.
  • Fig. 8 shows a block diagram of a recording and playback apparatus for digital signals of a second embodiment in accordance with the present invention.
  • Fig. 8 differs from Fig. 1 in that, an input selection circuit 13, and a digital-information input terminal 14 for a second mode are added, and compression encoding circuit 10 is deleted.
  • a recording mode is set by mode command generation circuit 8, and the set mode signal is input to tape-speed control circuit 7, input selection circuit 13, and magnetic-head selection circuit 11.
  • a digital-information input terminal 9 for a first mode and a digital-information input terminal 14 for a second mode are connected to input selection circuit 13.
  • Fig. 8 differ from Fig. 1 in that a recording mode is set by mode command generation circuit 8, and input selection circuit 13 selects an input signal applied to digital-information input terminal 9 in a first mode.
  • Magnetic-head selection circuit 11 selects a head of magnetic heads 3 so that the selected head performs recording during each scan. Further, tape-speed control circuit 7 controls the rotational speed of capstan motor 6 so that the traveling speed of magnetic tape 1 becomes a predetermined one.
  • input selection circuit 13 selects an input signal applied to digital-information input terminal 14, and magnetic-head selection circuit 11 selects a head of magnetic heads 3 so that magnetic heads 3 perform recording once every n scans and the azimuths of adjacent recorded tracks become different.
  • tape-speed control circuit 7 sets the traveling speed of the magnetic tape at 1/n the one in the first mode.
  • FIG. 9 Timing during recording a digital signal is shown in Figs. 9 and 10, where (a) denotes a head-switching signal, (b) denotes recorded tracks, and (c) denotes used heads and their intervals of recording.
  • Fig. 9 is a timing chart in the first recording mode (standard-play recording mode).
  • R1 and L1 of magnetic heads 3 are selected by magnetic-head selection circuit 11 for recording at the intervals where the head-switching signal is at "H”
  • R2 and L2 of magnetic heads 3 are selected for recording at the intervals where the head-switching signal is at "L”. Therefore, digital information input through digital-information input terminal 9 is recorded continuously on magnetic tape 1 using all the heads of magnetic heads 3, so that 4 tracks (R1, L1, R2, L2) are continuously recorded with track width Tp while rotary cylinder 2 makes one revolution.
  • the traveling speed of magnetic tape 1 is set by tape-speed control circuit 7 so that 4 tracks are recorded while rotary cylinder 2 makes one revolution. Since the azimuths of adjacent recorded tracks are different, recording can be made without any gap between adjacent tracks, so that high-density recording is made possible.
  • Fig. 10 is a timing chart in the second recording mode (long-play recording mode), in which the amount of digital information is 1/3 the amount of information for the first recording mode, and the amount of information of a signal input through digital-information input terminal 14 is 1/3 the amount for the first mode.
  • recording is performed while rotary cylinder 2 makes 1.5 revolutions, and the traveling speed of magnetic tape 1 becomes 1/3 the standard speed, since the amount of recorded information becomes 1/3 the amount for the first mode.
  • magnetic-head selection circuit 11 Since the rotational speed of rotary cylinder 2 is constant, two tracks are recorded on magnetic tape 1 while rotary cylinder 2 makes 1.5 revolutions. Therefore, as shown in (c) of Fig. 10, magnetic-head selection circuit 11 first selects (R1, L1) of magnetic heads 3, which perform recording. Next, after 1.5 revolutions of rotary cylinder 3, magnetic-head selection circuit 11 selects (R2, L2) of magnetic heads 3, which perform recording, and then, after 1.5 revolutions of rotary cylinder 3, magnetic-head selection circuit 11 selects (R1, L1) of magnetic heads 3, which perform recording. By repeating in this way, continuous recorded tracks are formed. In short, magnetic-head pairs (R1, L1) and (R2, L2) of magnetic heads 3 alternately perform recording once every 1.5 revolutions of rotary cylinder 2.
  • the traveling speed of magnetic tape 1 is 1/3 the tape speed in Fig. 9, since the amount of recorded information is 1/3 the amount for the first mode. Since the rotational speed of rotary cylinder 2 is constant, recording is continuously performed with the same track width Tp and without any gap between adjacent tracks as in Fig. 9 by recording two tracks while rotary cylinder 2 makes 1.5 revolutions. Recording is performed once while rotary cylinder 2 makes 1.5 revolutions, that is, while head pairs (R1, L1) and (R2, L2) of magnetic heads 3 scan three times in all. Since (R1, L1) and (R2, L2) are used alternately, the azimuths of adjacent tracks are different.
  • recorded tracks are scanned during playback once by magnetic heads 3 as during recording.
  • the amount of digital information becomes 1/n the amount for the first mode, so that, as in the first embodiment, tracking of high accuracy is not required during playback. Further, high-speed playback at up to n/2 times the standard speed is possible without loss of information.
  • magnetic heads 3 mounted in rotary cylinder 2 consist of two pairs of heads, one pair positioned opposite to the other at an angle of 180 degrees.
  • one head can be used in place of a pair of heads.
  • two pairs can be mounted in one position in stead of diametrically opposite positions.
  • the second mode described above may be a plurality of modes.
  • the traveling speed of magnetic tape 1 was changed depending on the amount of digital information in the second mode.
  • the tape speed is the same as in the first mode, then only gaps between adjacent recorded tracks occur, and the recording and playback apparatus works well without any problems.
  • Fig. 11 shows a block diagram of a recording and playback apparatus for digital signals of a third embodiment in accordance with the present invention.
  • Fig. 11 differs from Fig. 8 in that a rate instruction terminal 15, a bit-rate conversion circuit 16, and a system-information processing circuit 17 are added, and mode command generation circuit 8 and input selection circuit 13 are deleted.
  • a recording bit rate is set through rate instruction terminal 15 and an instruction signal of the set bit rate is input to tape-speed control circuit 7, bit-rate conversion circuit 16, system-information processing circuit 17, and magnetic-head selection circuit 11.
  • magnetic heads 3 mounted in rotary cylinder 2 are magnetic-head pairs (R1, L1) and (R2, L2), which are positioned opposite to each other at an angle of 180 degrees.
  • the relative heights of magnetic heads R1, L1, R2, L2 are set so that they are at the same height on the recorded pattern.
  • Bit-rate conversion circuit 16 converts the bit rate of digital information input through digital-information input terminal 9 into a predetermined recording bit rate by varying the frequencies of the write-clock and read-clock using a memory (not shown in Fig. 11) wherein a Table for designating an operation mode based on the system information input through the input terminal 15.
  • Figs. 12, 13, and 14 are recording timing charts that show the operations of a recording and playback apparatus for digital signals of the present invention, in case recording is performed converting the bit rate of an input signal into a recording bit rate.
  • FIGs. 12, 13, and 14 (a) denotes an input signal, (b) denotes a signal obtained from converting the bit rate of the input signal by bit-rate conversion circuit 16.
  • Each of the blocks Ai, Bi shows a piece of data which can be recorded during one scan of magnetic heads 3.
  • Magnetic-head recording signals, W-R1, W-L1, W-R2, and W-L2 are respectively expressing timing of recording by magnetic heads, R1, L1, R2, and L2, and are created by magnetic-head selection circuit 11. For example, a magnetic head performs recording at intervals when its recording signal is at "H".
  • bit rate of the input signal (about 36 Mbps) is almost the same as the recording bit rate (about 36 Mbps).
  • the bit-rate conversion by bit-rate conversion circuit 16 is not performed, and the input signal is recorded, as it is, on magnetic tape 1 by magnetic heads 3.
  • the block A1 of the input signal (a) becomes the block B1 of the recorded signal via bit-rate conversion circuit 16.
  • the block B1 of the recorded signal (b) is recorded at an immediate interval of the HSW signal, which is at "L",
  • the magnetic-head recording signal W-L2 is at "H”, so that the head L2 of the magnetic-head pair 3b is selected by magnetic-head selection circuit 11, and the magnetic head L2 records the block B1 of the recorded signal (b).
  • the block A2 of the input signal (a) becomes the block B2 of the recorded signal.
  • the block B2 of the recorded signal (b) is recorded at an immediate interval of the HSW signal, which is at "H"
  • the magnetic-head recording signal W-R1 is at "H”
  • the magnetic head R1 of the magnetic-head pair 3a records the block B2.
  • the blocks A3, A4, ... are recorded similarly. In this way the azimuths of adjacent tracks are made different, so that high-density recording without guard bands is made possible.
  • the traveling speed of magnetic tape 1 is set by tape-speed control circuit 7 controlling the rotational speed of capstan motor 6 so that recorded tracks become continuous.
  • bit rates of the input signal (a) and the recorded signal (b) are the same, recording is performed without the conversion of the bit rate by bit-rate conversion circuit 16. Also, magnetic heads 3 perform recording during each scan.
  • Figs. 15A, 15B and 15C respectively show track patterns realized when system information is recorded on magnetic tape 1 by system-information processing circuit 17.
  • Fig. 15A shows a track pattern in case system information is recorded near the ID area.
  • Fig. 15B shows a track pattern in case system information is recorded near the tracking area.
  • Fig. 15C shows a track pattern in case system information is recorded at almost the middle of a track.
  • the ID area is important, in which data necessary for searching and the like are usually stored. Therefore, if system information is recorded near the ID area, then system information is reproduced as ID information, and the mode during can be determined based on the system information.
  • the tracking area in which tracking information is stored is also important. If system information is recorded near the tracking area, then if tracking information can be reproduced, then system information can also be reproduced, and the mode during playback can be determined based on the system information.
  • system information is recorded in the middle of a track, then since the middle part is less affected by flaws, track bending, and the like than in a tape-edge part, system information can be reproduced more accurately.
  • the scanning information of magnetic heads 3 that is, information about once how many scans the magnetic heads performed recording, is recorded as system information, then the traveling speed of the magnetic tape and the number of scans required for recording one track are obtained during playback. Therefore, the conditions on playback can be made the same as on recording.
  • the tape-speed information that is, the traveling speed of magnetic tape 1
  • the traveling speed of magnetic tape 1 is recorded as system information
  • the traveling speed of magnetic tape 1 is recorded as system information
  • information about once how many scans magnetic heads 3 performed recording is obtained. Therefore, the conditions on playback can be made the same as on recording. For example, if the tape speed recorded as system information is 1/4 the tape speed for recording during each scan, then recording was performed once every 4 scans in the recording mode. In this way the conditions on recording can be restored.
  • bit-rate conversion circuit 16 converts the bit rate of the input signal into the bit rate of the recorded signal (9 Mbps ⁇ 36 Mbps). Therefore, after the input signal is time-compressed into its 1/4, the converted signal is recorded on magnetic tape 1 once every 4 scans of the magnetic heads. Therefore, controlled by tape-speed control circuit 7, the traveling speed of magnetic tape 1 is slowed down into 1/4 of the traveling speed in Fig. 12.
  • the block A1 of the input signal (a) becomes the block B1 of the recorded signal (b) via bit-rate conversion circuit 16, that is, time compression is performed.
  • the block B1 of the recorded signal (b) is recorded at an immediate interval of the HSW signal, which is at "H”. At this interval, the magnetic-head recording signal W-R1 is at "H", so that the head R1 of the magnetic-head pair 3a is selected by magnetic-head selection circuit 11, and the magnetic head R1 records the block B1 of the recorded signal (b).
  • the block A2 of the input signal (a) becomes the block B2 of the recorded signal.
  • the block B2 of the recorded signal (b) is recorded at an immediate interval of the HSW signal, which is at "H”.
  • the magnetic-head recording signal W-L1 is at "H"
  • the magnetic head L1 of the magnetic-head pair 3a records the block B2.
  • the blocks A3, A4, ... are recorded similarly. In this way the azimuths of adjacent tracks are made different, so that high-density recording without guard bands is made possible.
  • the blocks B1 and B2 of the recorded signal are performed intermittently. Specifically, recording is performed once every 4 scans of magnetic heads 3, that is, while rotary cylinder 2 makes two revolutions. Recording for the blocks A3, A4, A5 of the input signal are similarly intermittently performed.
  • bit-rate conversion circuit 16 converts the bit rate of the input signal into the bit rate of the recorded signal (4 Mbps ⁇ 36 Mbps). Since the input signal is time-compressed into its 1/9, recording is performed once every 9 scans of magnetic heads 3. Therefore, controlled by tape-speed control circuit 7, the traveling speed of magnetic tape 1 is slowed down into 1/9 of the traveling speed in Fig. 12.
  • the block A1 of the input signal (a) becomes the block B1 of the recorded signal (b) via bit-rate conversion circuit 16, that is, time compression is performed.
  • the block B1 of the recorded signal (b) is recorded at an immediate interval of the HSW signal, which is at "L”. At this interval, the magnetic-head recording signal W-L2 is at "H", so that the head L2 of the magnetic-head pair 3b is selected by magnetic-head selection circuit 11, and the magnetic head L2 records the block B1 of the recorded signal (b).
  • the block A2 of the input signal (a) becomes the block B2 of the recorded signal.
  • the block B2 of the recorded signal (b) is recorded at an immediate interval of the HSW signal, which is at "H”.
  • the magnetic-head recording signal W-R1 is at "H"
  • the magnetic head R1 of the magnetic-head pair 3a records the block B2.
  • the blocks B1 and B2 of the recorded signal are recorded intermittently. Specifically, recording is performed once every 9 scans of magnetic heads 3, that is, while rotary cylinder 2 makes 4.5 revolutions. Recording for the blocks A3, A4 of the input signal (a) are similarly intermittently performed.
  • bit-rate conversion circuit 16 adjusts the bit rate of the input signal to the bit rate of the recorded signal, and recording is performed once every several scans of magnetic heads 3, so that the bit rate of the recorded signal is made constant, and recording depending on the bit rate of the input signal is performed.
  • Fig. 16 is a playback block diagram of a recording and playback apparatus for digital signals of the third embodiment. If a component has the same function as in Fig. 11, the same symbol is used to denote it, and its redundant description is omitted.
  • magnetic-head selection circuit 11 selects a magnetic head to be used from the magnetic-head pairs 3a and 3b, and the output signal reproduced by the selected head is input to bit-rate conversion circuit 16, which converts the reproduced signal so that its bit rate is changed from the bit rate of the recorded signal into the bit rate of the original input signal. Then bit-rate conversion circuit 16 outputs the converted signal through output terminal 18.
  • the reproduced system information is processed by system-information processing circuit 17, and a playback mode is set.
  • Fig. 17 shows the timing of the operation in a playback mode and the track pattern on the magnetic tape traced by magnetic heads in a recording and playback apparatus for digital signals of the present embodiment.
  • T-P denotes recorded tracks.
  • HSW denotes a head-switching signal corresponding to the magnetic-head pairs 3a, 3b and expresses phases of rotation of rotary cylinder 2.
  • Signals R-R1, R-L1, R-R2, and R -L2 respectively express the timing of playback by the corresponding heads, R1, L1, R2, and L2, and each magnetic head is used for playback when the corresponding signal is at "H".
  • (c) denotes signal blocks reproduced at the recorded bit rate
  • (d) denotes signal blocks obtained after the bit rate is converted into the bit rate of the original digital signal.
  • Fig. 17 shows playback in case an input signal of 9 Mbps was recorded at a recorded bit rate of 36 Mbps.
  • the magnetic head R1 of the magnetic-head pair 3a is used for playback.
  • the magnetic head R2 of the magnetic-head pair 3b is used for playback.
  • the magnetic head L1 of the magnetic-head pair 3a and the magnetic head L2 of the magnetic-head pair 3b are used for playback.
  • the same track is scanned several times (4 times), but only a reproduced signal such that the recorded digital information is normally played back by a scan as a reproduced signal is used.
  • the first R-azimuth track is played back by the head R1 at time t1.
  • the next L-azimuth track is played back by the head L1 at time t5.
  • the mode during playback is made the same as during recording by reproducing the system information recorded on tracks to obtain information about the recording. If the mode during playback and the mode during recording are different, then by making the mode during playback the one such that the tape speed in that mode is the slowest, the number of scanning times by magnetic heads 3 is maximized, so that the recorded system information is easily obtained.
  • the switching of magnetic heads 3 can be determined by comparing the output of each head with each other and by selecting a magnetic head producing high levels of a reproduced signal. And, the mode during recording can be estimated from the timing of switching magnetic heads 3 and the traveling speed of magnetic tape 1. For example, the tape speed is doubled in Fig. 17, then the timing of switching the magnetic heads becomes twice as fast as the original one, and the switching of the magnetic heads changes from 4 times per track into 2 times per track. In this way, the information about the mode during recording can be obtained, but reproducing the recorded system information is better to obtain the system information steadily.
  • bit rate of the original input signal is 9 Mbps was described above using Fig. 17. However, an input signal of 4 Mbps is similarly played back. Further, playback in other cases is similarly realized.
  • Fig. 17 the same track is scanned several times (4 times) for playback, so that even if tracking is not accurate, information recorded on one track is obtained by one of 4 scans. Further, information recorded on one track can be composed by connecting pieces of information obtained by several scans. Therefore, rigorous tracking becomes unnecessary, and the control of the tape speed can be simplified.
  • a recording and playback apparatus for digital signals of a fourth embodiment in accordance with the present invention is described in the following.
  • the operations in recording modes of the fourth embodiment are almost the same as those in the first, second and the third embodiments such that magnetic heads perform recording once every n scans.
  • the recorded tracks are continuous without any gap, and the azimuths of adjacent tracks are different.
  • Fig. 18 is a playback block diagram of a recording and playback apparatus for digital signals of the fourth embodiment. If a component has the same function as in Fig. 1, the same symbol is used to denote it, and its redundant description is omitted.
  • the playback speed is set through a playback-speed instruction terminal 19, and an instruction signal of the set playback speed is input to tape-speed control circuit 7, a memory circuit 20, and magnetic-head selection circuit 11.
  • Magnetic-head selection circuit 11 selects a magnetic head to be used from the magnetic-pairs 3a and 3b mounted in rotary cylinder 2, and the output signal reproduced by the selected head is input to memory circuit 20.
  • Memory circuit 20 rearranges the reproduced signals so that the order becomes the same as in the input signal during recording. Then memory circuit 20 outputs the signal obtained by the rearrangement through output terminal 21.
  • magnetic heads 3 mounted in rotary cylinder 2 are magnetic-head pairs (R1, L1) and (R2, L2), which are positioned opposite to each other at an angle of 180 degrees.
  • the relative heights of the magnetic heads R1, L1, R2, L2 are set so that they are at the same height on the recorded pattern.
  • Figs. 19, 20, and 21 show the timing of operations in playback modes and track patterns on the magnetic tape traced by the magnetic heads in a recording and playback apparatus for digital signals of the present embodiment.
  • T-P denotes recorded tracks.
  • HSW denotes a head-switching signal corresponding to the magnetic-head pairs 3a, 3b and expresses phases of rotation of rotary cylinder 2.
  • Signals R-R1, R-L1, R-R2, and R-L2 respectively express the timing of playback by the corresponding heads, R1, L1, R2, and L2, and each magnetic head is used for playback when the corresponding signal is at "H".
  • Fig. 19 shows a case of the same playback speed as the recording speed.
  • the magnetic head R1 of the magnetic-head pair 3a is used for playback.
  • the magnetic head R2 of the magnetic-head pair 3b is used for playback.
  • the magnetic heads R1 and R2 are respectively used for playback.
  • the magnetic head L1 of the magnetic-head pair 3a and the magnetic head L2 of the magnetic-head pair 3b are used for playback.
  • the same track is scanned several times (8 times), but only a reproduced signal such that recorded digital information is normally played back by a scan as a reproduced signal is used.
  • the HSW signal is at "H", so that the magnetic-head pair 3a scans magnetic tape 1.
  • the azimuth of the recorded track on magnetic tape 1 is R, so that the R-R1 signal changes into “H”, and the magnetic head R1 of the magnetic-head pair 3a is used for playback. Therefore, the trace pattern of the magnetic-head pair 3a becomes as shown by the short dashes.
  • the HSW signal is at "L", so that the magnetic-head pair 3b scans magnetic tape 1.
  • the azimuth of the recorded track on magnetic tape 1 is L, so that the R-L2 signal changes into "H”, and the magnetic head L2 of the magnetic-head pair 3b is used for playback. Therefore, the trace pattern of the magnetic-head pair 3b becomes as shown by the short and long dashes.
  • the HSW signal is at "H", so that the magnetic-head pair 3a scans magnetic tape 1.
  • the azimuth of the recorded track on magnetic tape 1 is L, so that the R-L1 signal changes into “H”, and the magnetic head L1 of the magnetic-head pair 3a is used for playback.
  • the HSW signal is at "L", so that the magnetic-head pair 3b scans magnetic tape 1.
  • the azimuth of the recorded track on magnetic tape 1 is R, so that the R-R2 signal changes into "H”, and the magnetic head R2 of the magnetic-head pair 3b is used for playback.
  • the situation is the same as from time 1 to time t4.
  • an L-azimuth track is played back by both at time t2 and time t3 using the magnetic-head pairs 3b and 3a respectively. Therefore, digital information obtained from either one of the scans is used.
  • R-azimuth tracks of T-P are the same. In this way, all digital information on a track is obtained by one scan, so that the obtained digital information does not require rearrangement by memory circuit 20.
  • the HSW signal is at "H", so that the magnetic-head pair 3a scans magnetic tape 1.
  • the azimuth of the recorded track on magnetic tape 1 is R, so that the R-R1 signal changes into "H”, and the magnetic head R1 of the magnetic-head pair 3a is used for playback.
  • the track pattern traced by the magnetic-head pair 3a shifts from an R-azimuth track to an L-azimuth track as shown by the dashed line.
  • the playback outputs of the magnetic head R1 and the magnetic head L1 of the magnetic-head pair 3a become the same, and after that the playback output of the magnetic head L1 becomes greater than the playback output of the magnetic head R1. Therefore, at time t2, the R-L1 signal changes into "H", and the used magnetic head of the magnetic-head-pair 3a is switched from R1 to L1. As a result, the portion L-B of the recorded track L is played back at the time interval between t2 and t3.
  • the HSW signal is at "L", so that the magnetic-head pair 3b scans magnetic tape 1.
  • the azimuth of the recorded track on magnetic tape 1 is L, so that the R-L2 signal changes into "H”, and the magnetic head L2 of the magnetic-head pair 3b is used for playback.
  • the track pattern traced by the magnetic-head pair 3b shifts from an L-azimuth track to an R-azimuth track, so that, at time t4, the R-R2 signal changes into "H", and the used magnetic head of the magnetic-head-pair 3b is switched from L2 to R2.
  • the portion L-A of the recorded track L is played back at the time interval between t3 and t4. Therefore, by connecting the portion L-B played back at the time interval between t2 and t3 to L-A, the whole recorded track L is played back.
  • the order of their playback is the reverse of the recorded order, the reproduced pieces of digital information have to be rearranged using a memory.
  • the recorded digital information is reproduced as from time t1 to time t4.
  • the playback speed at which all recorded digital information is obtained can be faster than n times the recording speed. In this case, the playback speed at which all recorded digital information is obtained without rearrangement can be faster than n/2 the recording speed.
  • Figs. 22 and 23 show the timing of operations in playback modes and track patterns on the magnetic tape traced by the magnetic heads in a recording and playback apparatus for digital signals of the present embodiment.
  • magnetic heads 3 mounted in rotary cylinder 2 consist of two heads having different azimuths, one positioned opposite to the other at an angle of 180 degrees.
  • T-P denotes recorded tracks.
  • Signals R-R and R-L respectively express the timing of playback by the corresponding heads, R and L of magnetic heads 3, and each magnetic head is used for playback when the corresponding signal is at "H".
  • the R-R signal is at "H", so that the magnetic head R of magnetic heads 3 scans magnetic tape 1.
  • the track pattern traced by the magnetic head R becomes R-t1, and since the azimuth of the recorded track on magnetic tape 1 is R, the whole R-azimuth track is played back by one scan of the magnetic head R.
  • the R-L signal becomes "H", so that the magnetic head L of magnetic heads 3 is used for playback.
  • the track pattern traced by the magnetic head L becomes L-t2, and since the azimuth of the recorded track on magnetic tape 1 is L, the whole L-azimuth track is played back by one scan of the magnetic head L.
  • the R-R signal is at "H", so that the magnetic head R of magnetic heads 3 scans magnetic tape 1. and the track pattern traced by the magnetic head R becomes R-t1.
  • the magnetic head R is used to play back the recorded signal.
  • the track pattern traced by the magnetic head L becomes L-t2
  • an L-azimuth track of magnetic tape 1 is played back by the L-azimuth head of magnetic heads 3.
  • the head width of magnetic heads 3 is made wider than the track width, then the tracking margin is greater in case of a playback speed of n times the recording speed.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • Signal Processing For Digital Recording And Reproducing (AREA)
  • Digital Magnetic Recording (AREA)
EP94107527A 1993-05-17 1994-05-16 Appareil d'enregistrement et de reproduction de signaux numériques. Withdrawn EP0625850A3 (fr)

Applications Claiming Priority (10)

Application Number Priority Date Filing Date Title
JP114454/93 1993-05-17
JP5114454A JPH06325305A (ja) 1993-05-17 1993-05-17 ディジタル信号記録再生装置
JP5179013A JPH0737209A (ja) 1993-07-20 1993-07-20 ディジタル信号記録再生装置
JP179013/93 1993-07-20
JP5183712A JPH0744804A (ja) 1993-07-26 1993-07-26 ディジタル記録再生装置
JP183712/93 1993-07-26
JP05254083A JP3119053B2 (ja) 1993-10-12 1993-10-12 ディジタル信号記録再生装置
JP5254180A JPH07110903A (ja) 1993-10-12 1993-10-12 ディジタル信号記録再生装置
JP254180/93 1993-10-12
JP254083/93 1993-10-12

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EP0625850A2 true EP0625850A2 (fr) 1994-11-23
EP0625850A3 EP0625850A3 (fr) 1995-06-21

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EP0658880A4 (fr) * 1993-06-07 1995-04-18 Sony Corp Dispositif d'enregistrement et de lecture.
EP0649136A2 (fr) * 1993-10-15 1995-04-19 Matsushita Electric Industrial Co., Ltd. Une méthode d'enregistrement de données digitales, appareil d'enregistrement de données digitales, appareil de reproduction de données digitales, et appareil d'enregistrement et de reproduction de données digitales
EP0723377A2 (fr) * 1995-01-23 1996-07-24 Samsung Electronics Co., Ltd. Procédé d'enregistrement/de réproduction de bande vidéo numérique pour opération de lecture extraordinaire et dispositif d'enregistrement/de reproduction adapté à cet effet
EP0703715A3 (fr) * 1994-09-26 1997-06-25 Matsushita Electric Ind Co Ltd Appareil pour enregistrer des signaux numériques
EP0933762A2 (fr) * 1998-02-03 1999-08-04 Hitachi, Ltd. Appareil d'enregistrement et/ou de reproduction magnétique

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Cited By (21)

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EP0658880A1 (fr) * 1993-06-07 1995-06-21 Sony Corporation Dispositif d'enregistrement et de lecture
EP0658880A4 (fr) * 1993-06-07 1995-04-18 Sony Corp Dispositif d'enregistrement et de lecture.
US6038094A (en) * 1993-10-15 2000-03-14 Matsushita Electric Industrial Co., Ltd. Digital data recording device having a rotary cylinder
EP0649136A2 (fr) * 1993-10-15 1995-04-19 Matsushita Electric Industrial Co., Ltd. Une méthode d'enregistrement de données digitales, appareil d'enregistrement de données digitales, appareil de reproduction de données digitales, et appareil d'enregistrement et de reproduction de données digitales
US6508596B1 (en) 1993-10-15 2003-01-21 Matsushita Electric Industrial Co., Ltd. Apparatus using a method for recording digital data including a data conversion or format conversion, and apparatus using the method
EP0649136A3 (fr) * 1993-10-15 1997-05-14 Matsushita Electric Ind Co Ltd Une méthode d'enregistrement de données digitales, appareil d'enregistrement de données digitales, appareil de reproduction de données digitales, et appareil d'enregistrement et de reproduction de données digitales.
EP1043721A3 (fr) * 1993-10-15 2001-01-10 Matsushita Electric Industrial Co., Ltd. Méthode d'enregistrement de données digitales
US6147823A (en) * 1993-10-15 2000-11-14 Matsushita Electric Industrial Co., Ltd. Method for recording digital data including a data conversion or format conversion, and apparatus using the method
EP1043721A2 (fr) * 1993-10-15 2000-10-11 Matsushita Electric Industrial Co., Ltd. Méthode d'enregistrement de données digitales
EP1037210A1 (fr) * 1993-10-15 2000-09-20 Matsushita Electric Industrial Co., Ltd. Méthode d'enregistrement de données digitales
EP0703715A3 (fr) * 1994-09-26 1997-06-25 Matsushita Electric Ind Co Ltd Appareil pour enregistrer des signaux numériques
EP0891104A3 (fr) * 1994-09-26 1999-01-20 Matsushita Electric Industrial Co., Ltd Appareil pour enregistrer des signaux numériques
EP0891104A2 (fr) * 1994-09-26 1999-01-13 Matsushita Electric Industrial Co., Ltd Appareil pour enregistrer des signaux numériques
US5787221A (en) * 1994-09-26 1998-07-28 Matsushita Electric Industrial Co., Ltd. Digital signal recording apparatus
US6215950B1 (en) 1994-09-26 2001-04-10 Matsushita Electric Industrial Co., Ltd. Digital signal recording apparatus
US6295406B1 (en) 1994-09-26 2001-09-25 Matsushita Electric Industrial Co., Ltd. Digital signal recording apparatus for sampling and compressing signals according to various recording modes
EP0723377A3 (fr) * 1995-01-23 1999-10-06 Samsung Electronics Co., Ltd. Procédé d'enregistrement/de réproduction de bande vidéo numérique pour opération de lecture extraordinaire et dispositif d'enregistrement/de reproduction adapté à cet effet
EP0723377A2 (fr) * 1995-01-23 1996-07-24 Samsung Electronics Co., Ltd. Procédé d'enregistrement/de réproduction de bande vidéo numérique pour opération de lecture extraordinaire et dispositif d'enregistrement/de reproduction adapté à cet effet
EP1414251A1 (fr) * 1995-01-23 2004-04-28 Samsung Electronics Co., Ltd. Procédé de reproduction de bande vidéo numérique pour opération de lecture spéciale et dispositif de reproduction adapté à cet effet
EP0933762A2 (fr) * 1998-02-03 1999-08-04 Hitachi, Ltd. Appareil d'enregistrement et/ou de reproduction magnétique
EP0933762A3 (fr) * 1998-02-03 2002-03-20 Hitachi, Ltd. Appareil d'enregistrement et/ou de reproduction magnétique

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EP0625850A3 (fr) 1995-06-21

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